Impact of EGFR tyrosine kinase inhibitors versus chemotherapy on the development of leptomeningeal metastasis in never smokers with advanced adenocarcinoma of the lung

This study investigated whether epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) increase the development of leptomeningeal metastasis (LM) compared with standard chemotherapy in EGFR mutation-enriched non- small cell lung cancer. The incidence of LM was longitudinally assessed in never smokers with advanced adenocarcinoma of the lung enrolled in a phase III randomized controlled study that compared gefitinib with gemcitabine plus cisplatin (GP) as first-line therapy (The First-SIGNAL study). Among 203 patients who were enrolled at the National Cancer Center Hospital (Goyang, Republic of Korea), LM occurred in 32 (15.8 %) with a minimum follow-up time of 55.1 months. The 1-, 2-, and 3-year actuarial incidence rates of LM were 5.3, 10.6, and 24.6 %, respectively. During first-line treatment, LM occurred in 2 patients (2.0 %) treated with gefitinib and in 3 patients (3.2 %) treated with GP. There was no difference in the incidence of LM during first-line treatment between the two groups (P = 0.934). The incidence of LM was significantly increased during second-line EGFR-TKI treatment compared with first-line EGFR-TKI treatment (P = 0.041). During the disease course, the cumulative incidence of LM was not significantly different between the two treatment groups (P = 0.514). The median time to LM was 21.4 and 24.0 months in the gefitinib and GP groups, respectively (P = 0.895). Similar trends were observed in the subset analysis with 23 EGFR-mutant patients. In conclusion, LM predominantly occurred in the late phase of disease in this population. EGFR-TKIs did not affect the incidence or timing of LM development.